Results for "J. Skowron"

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The influence of weak lensing on measurements of the Hubble constant with quad-image gravitational lensesJul 21 2016We investigate the influence of matter along the line of sight and in the strong lens vicinity on the properties of quad image configurations and on the measurements of the Hubble constant (H0). We use simulations of light propagation in a nonuniform ... More
General Complex Polynomial Root Solver and Its Further Optimization for Binary MicrolensesMar 05 2012We present a new algorithm to solve polynomial equations, and publish its code, which is 1.6-3 times faster than the ZROOTS subroutine that is commercially available from Numerical Recipes, depending on application. The largest improvement, when compared ... More
OGLE-ing the Magellanic System: Cepheids in the BridgeApr 17 2019We present a detailed analysis of Magellanic Bridge Cepheid sample constructed using the OGLE Collection of Variable Stars. Our updated Bridge sample contains 10 classical and 13 anomalous Cepheids. We calculate their individual distances using optical ... More
Proportional Approval Voting, Harmonic k-median, and Negative AssociationApr 07 2017Mar 12 2018We study a generic framework that provides a unified view on two important classes of problems: (i) extensions of the k-median problem where clients are interested in having multiple facilities in their vicinity (e.g., due to the fact that, with some ... More
Generation of Schrödinger's cat states in a planar semiconductor heterostructureOct 20 2016We propose a nanodevice based on a typical planar semiconductor heterostructure with lateral confinement potential created by voltages applied to local electrodes. We show how to obtain near parabolical confinement along the nanodevice, and how to use ... More
Repeating microlensing events in the OGLE dataNov 17 2008Microlensing events are usually selected among single-peaked non-repeating light curves in order to avoid confusion with variable stars. However, a microlensing event may exhibit a second microlensing brightening episode when the source or/and the lens ... More
Multiwinner Analogues of Plurality Rule: Axiomatic and Algorithmic PerspectivesFeb 28 2016We characterize the class of committee scoring rules that satisfy the fixed-majority criterion. In some sense, the committee scoring rules in this class are multiwinner analogues of the single-winner Plurality rule, which is uniquely characterized as ... More
FPT Approximation Schemes for Maximizing Submodular FunctionsOct 01 2015We investigate the existence of approximation algorithms for maximization of submodular functions, that run in fixed parameter tractable (FPT) time. Given a non-decreasing submodular set function $v: 2^X \to \mathbb{R}$ the goal is to select a subset ... More
What Do We Elect Committees For? A Voting Committee Model for Multi-Winner RulesNov 21 2016We present a new model that describes the process of electing a group of representatives (e.g., a parliament) for a group of voters. In this model, called the voting committee model, the elected group of representatives runs a number of ballots to make ... More
Proportionality Degree of Multiwinner RulesOct 20 2018We study multiwinner elections with approval-based preferences. An instance of a multiwinner election consists of a set of alternatives, a population of voters---each voter approves a subset of alternatives, and the desired committee size $k$; the goal ... More
Multi-Mode and Non-Standard Classical Cepheids in the Magellanic SystemJan 08 2016Jan 19 2016We present a sample of the most interesting classical Cepheids selected from the OGLE collection of classical Cepheids in the Magellanic System. The main selection criterion for this sample was the presence of non-standard, unique pulsational properties. ... More
Period-Luminosity Relations for Ellipsoidal Binary Stars in the OGLE-III Fields of the Large Magellanic CloudDec 08 2014We report the discovery of two distinct types of ellipsoidal binary systems occupying, so called, sequence E on the period-luminosity (P-L) diagram. We propose that steeper P-L relation is composed of giant-dwarf binaries, while the other consists of ... More
The awakening of a classical nova from hibernationAug 16 2016Cataclysmic variable stars (CVs) are close binary systems consisting of a white dwarf (primary) that is accreting matter from a low-mass companion star (secondary). From time to time such systems undergo large-amplitude brightenings. The most spectacular ... More
Blazhko-type modulation in the double-mode RR Lyrae stars of the OGLE Galactic bulge collectionNov 10 2014Dec 16 2014We present the analysis of Blazhko-type modulation in double-mode RR Lyrae (RRd) stars found in the OGLE photometry of the Galactic bulge. Modulation is detected in 15 stars. Most of them have non-typical period ratio of the radial modes. In the Petersen ... More
Over 38000 RR Lyrae Stars in the OGLE Galactic Bulge FieldsOct 06 2014We present the most comprehensive picture ever obtained of the central parts of the Milky Way probed with RR Lyrae variable stars. This is a collection of 38257 RR Lyr stars detected over 182 square degrees monitored photometrically by the Optical Gravitational ... More
Eclipsing Binaries with Classical Cepheid Component in the Magellanic SystemJan 07 2016We present a census of eclipsing binary systems with classical Cepheid as a component. All such systems known were found in the OGLE collection of classical Cepheids in the Magellanic System. We extend the list of potential candidates adding four new ... More
OGLE Collection of Galactic CepheidsOct 22 2018We present here a new major part of the OGLE Collection of Variable Stars - OGLE Collection of Galactic Cepheids. The new dataset was extracted from the Galaxy Variability Survey images - a dedicated large-scale survey of the Galactic disk and outer bulge ... More
Three-Dimensional Distributions of Type II Cepheids and Anomalous Cepheids in the Magellanic Clouds. Do these Stars Belong to the Old, Young or Intermediate-Age Population?Sep 05 2018Oct 24 2018The nature of type II Cepheids and anomalous Cepheids is still not well known and their evolutionary channels leave many unanswered questions. We use complete collection of classical pulsating stars in the Magellanic Clouds discovered by the OGLE project, ... More
Gaia and Variable StarsNov 24 2016We present a comparison of the Gaia DR1 samples of pulsating variable stars - Cepheids and RR Lyrae type - with the OGLE Collection of Variable Stars aiming at the characterization of the Gaia mission performance in the stellar variability domain. Out ... More
OGLE-ing the Magellanic System: Photometric Metallicity from Fundamental Mode RR Lyrae StarsJul 29 2016Nov 08 2016In an era of extensive photometric observations, the catalogs of RR Lyr type variable stars number tens of thousands of objects. The relation between the iron abundance [Fe/H] and the Fourier parameters of the stars light curve allows us to investigate ... More
OGLE-ing the Magellanic System: Photometric Metallicity from Fundamental Mode RR Lyrae StarsJul 29 2016In an era of extensive photometric observations, the catalogs of RR Lyrae type variable stars number tens of thousands of objects. The relation between the iron abundance [Fe/H] and the Fourier parameters of the stars light curve allows us to investigate ... More
The OGLE Collection of Variable Stars. Classical Cepheids in the Magellanic SystemJan 06 2016Jan 19 2016We present here a nearly complete census of classical Cepheids in the Magellanic System. The sample extends the set of Cepheids published in the past by the Optical Gravitational Lensing Experiment (OGLE) to the outer regions of the Large (LMC) and Small ... More
Deciphering the 3D structure of the old Galactic bulge from the OGLE RR Lyrae starsDec 12 2014Sep 16 2015We have analyzed a sample of 27,258 fundamental-mode RR Lyrae variable stars (type RRab) detected recently toward the Galactic bulge by the Optical Gravitational Lensing Experiment (OGLE) survey. The data support our earlier claim that these metal-poor ... More
The OGLE Collection of Variable Stars. Over 45 000 RR Lyrae Stars in the Magellanic SystemJun 08 2016Jul 14 2016We present the largest collection of RR Lyrae stars in the Magellanic System and in its foreground. The sample consists of 45 451 RR Lyr stars, of which 39 082 were detected toward the Large Magellanic Cloud and 6369 toward the Small Magellanic Cloud. ... More
The OGLE Collection of Variable Stars. Anomalous Cepheids in the Magellanic CloudsAug 04 2015We present a collection of 250 anomalous Cepheids (ACs) discovered in the OGLE-IV fields toward the Large (LMC) and Small Magellanic Cloud (SMC). The LMC sample is an extension of the OGLE-III Catalog of ACs published in 2008, while the SMC sample contains ... More
A New 3-D Picture of the Milky Way with Classical CepheidsJun 27 2018Aug 16 2018The global view of the Milky Way as a barred spiral galaxy was inferred from various tracers, e.g., star counts or radio maps of Galactic gas, as well as from our extrapolation of structures seen in other galaxies. However, distances to these tracers ... More
OGLE-LMC-ECL-09937: The Most Massive Algol-Type Binary System With A Mass Measurement Accurate to 2%Jan 17 2018This paper presents a detailed analysis of the light and radial velocity curves of the semi-detached eclipsing binary system OGLE-LMC-ECL-09937. The system is composed of a hot, massive and luminous primary star of a late-O spectral type, and a more evolved, ... More
SDWFS-MT-1: A Self-Obscured Luminous Supernova at z~0.2Jun 21 2010Sep 05 2010We report the discovery of a six-month-long mid-infrared transient, SDWFS-MT-1 (aka SN 2007va), in the Spitzer Deep, Wide-Field Survey of the NOAO Deep Wide-Field Survey Bootes field. The transient, located in a z=0.19 low luminosity (M_[4.5]~-18.6 mag, ... More
Discovery and Follow-up of the Unusual Nuclear Transient OGLE17aajJan 11 2019We report on the discovery and follow-up of a peculiar transient, OGLE17aaj, which occurred in the nucleus of a weakly active galaxy. We investigate whether it can be interpreted as a new candidate for a tidal disruption event (TDE). We present the OGLE-IV ... More
Consistent Approval-Based Multi-Winner RulesApr 08 2017May 12 2018This paper is an axiomatic study of consistent approval-based multi-winner rules, i.e., voting rules that select a fixed-size group of candidates based on approval ballots. We introduce the class of counting rules, provide an axiomatic characterization ... More
Multi-Attribute Proportional RepresentationSep 11 2015We consider the following problem in which a given number of items has to be chosen from a predefined set. Each item is described by a vector of attributes and for each attribute there is a desired distribution that the selected set should have. We look ... More
Exploring heterogeneity of unreliable machines for p2p backupDec 03 2012Apr 20 2013P2P architecture is a viable option for enterprise backup. In contrast to dedicated backup servers, nowadays a standard solution, making backups directly on organization's workstations should be cheaper (as existing hardware is used), more efficient (as ... More
Network delay-aware load balancing in selfish and cooperative distributed systemsDec 03 2012We consider a request processing system composed of organizations and their servers connected by the Internet. The latency a user observes is a sum of communication delays and the time needed to handle the request on a server. The handling time depends ... More
We Are Impatient: Algorithms for Geographically Distributed Load Balancing with (Almost) Arbitrary Load FunctionsFeb 10 2014In geographically-distributed systems, communication latencies are non-negligible. The perceived processing time of a request is thus composed of the time needed to route the request to the server and the true processing time. Once a request reaches a ... More
Non-monetary fair scheduling---a cooperative game theory approachFeb 05 2013Apr 22 2014We consider a multi-organizational system in which each organization contributes processors to the global pool but also jobs to be processed on the common resources. The fairness of the scheduling algorithm is essential for the stability and even for ... More
The ASAS-SN Bright Supernova Catalog $-$ I. 2013$-$2014Apr 01 2016Dec 13 2016We present basic statistics for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during its first year-and-a-half of operations, spanning 2013 and 2014. We also present the same information for all other bright ($m_V\leq17$), ... More
OGLE-BLG182.1.162852: An Eclipsing Binary with a Circumstellar DiskOct 09 2014We present the discovery of a plausible disk-eclipse system OGLE-BLG182.1.162852. The OGLE light curve for OGLE-BLG182.1.162852 shows three episodes of dimming by $I \simeq 2 - 3$ magnitudes, separated by 1277 days. The shape of the light curve during ... More
Approximating the MaxCover Problem with Bounded Frequencies in FPT TimeSep 17 2013We study approximation algorithms for several variants of the MaxCover problem, with the focus on algorithms that run in FPT time. In the MaxCover problem we are given a set N of elements, a family S of subsets of N, and an integer K. The goal is to find ... More
Approval-Based Elections and Distortion of Voting RulesJan 20 2019We consider elections where both voters and candidates can be associated with points in a metric space and voters prefer candidates that are closer to those that are farther away. It is often assumed that the optimal candidate is the one that minimizes ... More
Comparing Election Methods Where Each Voter Ranks Only Few CandidatesJan 30 2019Election rules are formal processes that aggregate voters preferences, typically to select a single candidate, called the winner. Most of the election rules studied in the literature require the voters to rank the candidates from the most to the least ... More
A Quantitative Analysis of Multi-Winner RulesJan 04 2018May 12 2018To choose a suitable multi-winner rule, i.e., a voting rule for selecting a subset of $k$ alternatives based on a collection of preferences, is a hard and ambiguous task. Depending on the context, it varies widely what constitutes the choice of an "optimal" ... More
OGLE Collection of Star Clusters. New Objects in the Outskirts of the Large Magellanic CloudSep 26 2016The Magellanic System (MS), consisting of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the Magellanic Bridge (MBR), contains diverse sample of star clusters. Their spatial distribution, ages and chemical abundances may provide ... More
Two Stars Two Ways: Confirming a Microlensing Binary Lens Solution with a Spectroscopic Measurement of the OrbitJun 04 2015Light curves of microlensing events involving stellar binaries and planetary systems can provide information about the orbital elements of the system due to orbital modulations of the caustic structure. Accurately measuring the orbit in either the stellar ... More
Anomalous Double-Mode RR Lyrae Stars in the Magellanic CloudsAug 01 2016We report the discovery of a new subclass of double-mode RR Lyrae stars in the Large and Small Magellanic Clouds. The sample of 22 pulsating stars have been extracted from the latest edition of the OGLE collection of RR Lyrae variables in the Magellanic ... More
Intriguing triple-mode RR Lyrae star with period doublingNov 11 2014Dec 22 2014We report the discovery of an intriguing triple-mode RR Lyrae star found in the OGLE Galactic bulge collection, OGLE-BLG-RRLYR-24137. In the OGLE catalog the star was identified as RRd star - double-mode pulsator, pulsating simultaneously in the fundamental ... More
OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge Using RR Lyrae StarsNov 08 2016We present a three-dimensional analysis of a sample of 22 859 type $ab$ RR Lyrae stars in the Magellanic System from the OGLE-IV Collection of RR Lyrae stars. The distance to each object was calculated based on its photometric metallicity and a theoretical ... More
OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge Using RR Lyrae StarsNov 08 2016Jul 10 2017We present a three-dimensional analysis of a sample of 22 859 type $ab$ RR Lyrae stars in the Magellanic System from the OGLE-IV Collection of RR Lyrae stars. The distance to each object was calculated based on its photometric metallicity and a theoretical ... More
$12\;660$ spotted stars toward the OGLE Galactic bulge fieldsMar 13 2019We present the discovery and statistical analysis of $12\;660$ spotted variable stars toward and inside the Galactic bulge from over two-decade-long Optical Gravitational Lensing Experiment (OGLE) data. We devise a new method of dereddening of individual ... More
OGLE Collection of Star Clusters. New Objects in the Magellanic Bridge and the Outskirts of the Small Magellanic CloudJan 17 2018The Magellanic System (MS) encompasses the nearest neighbors of the Milky Way, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic Bridge (MBR). This system contains a diverse sample of star clusters. Their parameters, such as the spatial ... More
OGLE-ing the Magellanic System: Stellar populations in the Magellanic BridgeMay 28 2014Sep 30 2014We report the discovery of a young stellar bridge, that forms a continuous connection between the Magellanic Clouds. This finding is based on number density maps for stellar populations found in data gathered by OGLE-IV, that fully cover over 270 deg^2 ... More
OGLE-ing the Magellanic System: RR Lyrae Stars in the BridgeApr 16 2019We use the extended and updated OGLE Collection of Variable Stars to thoroughly analyze distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive absolute Wesenheit magnitude and then individual distance of each ... More
OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge Using Classical CepheidsFeb 29 2016Jul 12 2016We analyzed a sample of 9418 fundamental-mode and first-overtone Classical Cepheids from the OGLE-IV Collection of Classical Cepheids. The distance to each Cepheid was calculated using the period-luminosity relation for the Wesenheit magnitude, fitted ... More
Recurrent and symbiotic novae in the OGLE dataMay 08 2014Jul 18 2014We analyse long-term optical photometry for two Galactic recurrent novae (V745 Sco and V3890 Sgr) and one Large Magellanic Cloud object (Nova LMC 1990b) observed over several years by the Optical Gravitational Lensing Experiment (OGLE) sky survey. We ... More
The Optical Gravitational Lensing Experiment. Dwarf Novae in the OGLE Data. I. Three New Dwarf Novae: One in the Period Gap and Two Longer Period ObjectsJul 12 2011We report serendipitous discovery of three new dwarf novae which eruptions in 2010 were observed by the ongoing microlensing survey OGLE-IV. All three objects are located in the Galactic bulge fields observed with the highest cadence of 20 minutes. In ... More
The OGLE View of Microlensing towards the Magellanic Clouds. IV. OGLE-III SMC Data and Final Conclusions on MACHOsJun 15 2011In this fourth part of the series presenting the Optical Gravitational Lensing Experiment (OGLE) microlensing studies of the dark matter halo compact objects (MACHOs) we describe results of the OGLE-III monitoring of the Small Magellanic Cloud (SMC). ... More
The OGLE View of Microlensing towards the Magellanic Clouds. I. A Trickle of Events in the OGLE-II LMC dataMay 13 2009We present the results from the OGLE-II survey (1996-2000) towards the Large Magellanic Cloud (LMC), which has the aim of detecting the microlensing phenomena caused by dark matter compact objects in the Galactic Halo (Machos). We use high resolution ... More
Binary Lenses in OGLE III EWS Database. Season 2005Feb 25 2008We present nine new binary lens candidates from OGLE-III Early Warning System database for the season of 2005. We have also found four events interpreted as single mass lensing of double sources. The candidates have been selected by visual light curves ... More
Binary Lenses in OGLE-III EWS Database. Season 2004Jan 31 2007We present 19 binary lens candidates from OGLE-III Early Warning System database for the season of 2004. We have also found five events interpreted as single mass lensing of double sources. The candidates have been selected by visual light curves inspection. ... More
OGLE-2014-BLG-0257L: A Microlensing Brown Dwarf Orbiting a Low-mass M DwarfMar 15 2016In this paper, we report the discovery of a binary composed of a brown dwarf and a low-mass M dwarf from the observation of the microlensing event OGLE-2014-BLG-0257. Resolution of the very short-lasting caustic crossing combined with the detection of ... More
OGLE Study of the Sagittarius Dwarf Spheroidal Galaxy and its M54 Globular ClusterMay 16 2016Jul 14 2016We use the fundamental-mode RR Lyr-type variable stars (RRab) from OGLE-IV survey to draw a 3D picture of the central part of the tidally disrupted Sagittarius Dwarf Spheroidal (Sgr dSph) galaxy. We estimate the line-of-sight thickness of the Sgr dSph ... More
No Evidence for Classical Cepheids and a New Dwarf Galaxy Behind the Galactic DiskOct 28 2015Based on data from the ongoing OGLE Galaxy Variability Survey (OGLE GVS) we have verified observed properties of stars detected by the near-infrared VVV survey in a direction near the Galactic plane at longitude l~-27 deg and recently tentatively classified ... More
OGLE Atlas of Classical Novae I. Galactic Bulge ObjectsApr 30 2015Jul 28 2015Eruptions of classical novae are possible sources of lithium formation and gamma-ray emission. Nova remnants can also become Type Ia supernovae (SNe Ia). The contribution of novae to these phenomena depends on nova rates, which are not well established ... More
Dwarf Novae in the OGLE Data. II. Forty New Dwarf Novae in the OGLE-III Galactic Disk FieldsJul 04 2013Aug 02 2013We report the discovery of forty erupting cataclysmic variable stars in the OGLE-III Galactic disk fields: seventeen objects of U Gem type, four of Z Cam type, and nineteen stars showing outbursts and superoutbursts typical for SU UMa type dwarf novae. ... More
Eclipsing Binary Stars in the OGLE-III Galactic Disk FieldsJun 26 2013Aug 02 2013We present the analysis of 11 589 eclipsing binary stars identified in twenty-one OGLE-III Galactic disk fields toward constellations of Carina, Centaurus, and Musca. All eclipsing binaries but 402 objects are new discoveries. The binaries have out-of-eclipse ... More
OGLE-2013-BLG-0578L: Microlensing Binary Composed of A Brown Dwarf And An M DwarfMar 11 2015Determining physical parameters of binary microlenses is hampered by the lack of information about the angular Einstein radius due to the difficulty of resolving caustic crossings. In this paper, we present the analysis of the binary microlensing event ... More
Supernovae and Other Transients in the OGLE-IV Magellanic Bridge DataJan 16 2013Apr 11 2013We analyze two years (mid-2010 to mid-2012) of OGLE-IV data covering ~65 deg^2 of the Magellanic Bridge (the area between the Magellanic Clouds) and find 130 transient events including 126 supernovae (SNe), two foreground dwarf novae and another two SNe-like ... More
The OGLE View of Microlensing towards the Magellanic Clouds. II. OGLE-II SMC dataApr 29 2010Apr 30 2010The primary goal of this paper is to provide the evidence that can either prove or falsify the hypothesis that dark matter in the Galactic halo can clump into stellar-mass compact objects. If such objects existed, they would act as lenses to external ... More
OGLE Atlas of Classical Novae. II. Magellanic CloudsNov 19 2015Jan 07 2016The population of classical novae in the Magellanic Clouds was poorly known because of a lack of systematic studies. There were some suggestions that nova rates per unit mass in the Magellanic Clouds were higher than in any other galaxy. Here, we present ... More
One Thousand New Dwarf Novae from the OGLE SurveyJan 11 2016We present one of the largest collections of dwarf novae (DNe) containing 1091 objects that have been discovered in the long-term photometric data from the Optical Gravitational Lensing Experiment (OGLE) survey. They were found in the OGLE fields toward ... More
The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. XV. Long-Period Variables in the Galactic BulgeApr 09 2013The fifteenth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains 232,406 long-period variables (LPVs) detected in the OGLE-II and OGLE-III fields toward the Galactic bulge. The sample consists of 6528 Mira stars, 33,235 semiregular variables ... More
The Optical Gravitational Lensing Experiment. Optical Counterparts to the X-ray Sources in the Galactic BulgeAug 01 2012We present a sample of 209 variable objects - very likely optical counterparts to the X-ray sources detected in the direction of the Galactic center by the Galactic Bulge Survey (GBS) carried out with the Chandra satellite. The variable sources were found ... More
Large Variety of New Pulsating Stars in the OGLE-III Galactic Disk FieldsNov 22 2013Jan 15 2014We present the results of a search for pulsating stars in the 7.12 deg^2 OGLE-III Galactic disk area in the direction tangent to the Centaurus Arm. We report the identification of 20 Classical Cepheids, 45 RR Lyr type stars, 31 Long-Period Variables, ... More
Analysis of photometric uncertainties in the OGLE-IV Galactic Bulge microlensing survey dataApr 07 2016We present a statistical assessment of both, observed and reported, photometric uncertainties in the OGLE-IV Galactic bulge microlensing survey data. This dataset is widely used for the detection of variable stars, transient objects, discovery of microlensing ... More
OGLE-BLG-RRLYR-12245: An RR Lyrae Star that Switched from a Double- to Single-mode PulsationMar 25 2014We report the discovery of an RR Lyrae star that experienced a switching of its pulsation mode. OGLE-BLG-RRLYR-12245 was discovered as a double-mode RRd star from the observations conducted in years 2001-2006 during the third phase of the Optical Gravitational ... More
Eclipsing Binary Stars in the OGLE-III Fields of the Small Magellanic CloudOct 11 2013We present a large sample of eclipsing binary stars detected in the Small Magellanic Cloud fields covering about 14 square degrees that have been monitored for eight years during the third phase of the OGLE survey. This is the largest set of such variables ... More
The Optical Gravitational Lensing Experiment. Gaia South Ecliptic Pole Field as Seen by OGLE-IVOct 03 2012Nov 09 2012We present a comprehensive analysis of the Gaia South Ecliptic Pole (GSEP) field, 5.3 square degrees area around the South Ecliptic Pole on the outskirts of the LMC, based on the data collected during the fourth phase of the Optical Gravitational Lensing ... More
The OGLE View of Microlensing towards the Magellanic Clouds. III. Ruling out sub-solar MACHOs with the OGLE-III LMC dataDec 06 2010Dec 08 2010In the third part of the series presenting the Optical Gravitational Lensing Experiment (OGLE) microlensing studies of the dark matter halo compact objects (MACHOs) we describe results of the OGLE-III monitoring of the Large Magellanic Cloud (LMC). This ... More
Binary Lenses in OGLE-III EWS Database. Seasons 2006--2008Sep 28 2010We present 27 binary lens candidates from OGLE-III Early Warning System database for the seasons 2006--2008. The candidates have been selected by visual light curves inspection. Our sample of binary lens events consists now of 78 stellar systems and 7 ... More
Extracting Microlensing Signals from K2 Campaign 9Apr 27 2017Aug 20 2017The reduction of the \emph{K2}'s Campaign 9 (K2C9) microlensing data is challenging mostly because of the very crowded field and the unstable pointing of the spacecraft. In this work, we present the first method that can extract microlensing signals from ... More
Discovery of two quasars at $z=5$ from the OGLE SurveyOct 19 2018We have used deep Optical Gravitational Lensing Experiment (OGLE-IV) images ($V \lesssim 23$ mag, $I \lesssim 23$ mag at $3\sigma$) of the Magellanic System, encompassing an area of $\sim$670 deg$^2$, to perform a search for high-$z$ quasar candidates. ... More
OGLE-2013-BLG-0102LA,B: Microlensing binary with components at star/brown-dwarf and brown-dwarf/planet boundariesJul 30 2014Nov 04 2014We present the analysis of the gravitational microlensing event OGLE-2013-BLG-0102. The light curve of the event is characterized by a strong short-term anomaly superposed on a smoothly varying lensing curve with a moderate magnification $A_{\rm max}\sim ... More
Axiomatic Characterization of Committee Scoring RulesApr 06 2016We provide an axiomatic characterization of committee scoring rules, analogues of the scoring rules for the multiwinner elections. We show that committee scoring rules are characterized by the set of four standard axioms, anonymity, neutrality, consistency ... More
Cooperation and Competition when Bidding for Complex Projects: Centralized and Decentralized PerspectivesFeb 12 2014Sep 15 2016To successfully complete a complex project, be it a construction of an airport or of a backbone IT system, agents (companies or individuals) must form a team having required competences and resources. A team can be formed either by the project issuer ... More
Structure and stability of online chat networks built on emotion-carrying linksSep 21 2012High-resolution data of online chats are studied as a physical system in laboratory in order to quantify collective behavior of users. Our analysis reveals strong regularities characteristic to natural systems with additional features. In particular, ... More
Axiomatic Characterization of Committee Scoring RulesApr 06 2016Nov 02 2016Committee scoring rules form a rich class of aggregators of voters' preferences for the purpose of selecting subsets of objects with desired properties, e.g., a shortlist of candidates for an interview, a representative collective body such as a parliament, ... More
Achieving Fully Proportional Representation is Easy in PracticeJan 27 2013We provide experimental evaluation of a number of known and new algorithms for approximate computation of Monroe's and Chamberlin-Courant's rules. Our experiments, conducted both on real-life preference-aggregation data and on synthetic data, show that ... More
Fully Proportional Representation as Resource Allocation: Approximability ResultsAug 08 2012Jan 27 2013We model Monroe's and Chamberlin and Courant's multiwinner voting systems as a certain resource allocation problem. We show that for many restricted variants of this problem, under standard complexity-theoretic assumptions, there are no constant-factor ... More
Stable Marriage with Multi-Modal PreferencesJan 08 2018We introduce a generalized version of the famous Stable Marriage problem, now based on multi-modal preference lists. The central twist herein is to allow each agent to rank its potentially matching counterparts based on more than one "evaluation mode" ... More
Finding a Collective Set of Items: From Proportional Multirepresentation to Group RecommendationFeb 13 2014Jan 08 2016We consider the following problem: There is a set of items (e.g., movies) and a group of agents (e.g., passengers on a plane); each agent has some intrinsic utility for each of the items. Our goal is to pick a set of $K$ items that maximize the total ... More
Matchings under Preferences: Strength of Stability and Trade-offsFeb 15 2019We propose two solution concepts for matchings under preferences: robustness and near stability. The former strengthens while the latter relaxes the classic definition of stability by Gale and Shapley (1962). Informally speaking, robustness requires that ... More
A Gravitationally Lensed Quasar Discovered in OGLEJan 25 2018We report the discovery of a new gravitationally lensed quasar (double) from the Optical Gravitational Lensing Experiment (OGLE) identified inside the $\sim$670 sq. deg area encompassing the Magellanic Clouds. The source was selected as one of $\sim$60 ... More
Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740LbMay 01 2019We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of $\Delta\chi^2\sim 4630$, but the interpretation of the signal suffers from two types of degeneracies. One type is caused by the ... More
Multiwinner Approval Rules as Apportionment MethodsNov 26 2016We establish a link between multiwinner elections and apportionment problems by showing how approval-based multiwinner election rules can be interpreted as methods of apportionment. We consider several multiwinner rules and observe that they induce apportionment ... More
Systems described by Volterra type integral operatorsNov 19 2013In the paper some sufficient condition for the nonlinear integral operator of the Volterra type to be a diffeomorphism defined on the space of absolutely continuous functions are formulated. The proof relies on consideration of the linearized equation ... More
OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing EventMar 30 2019Apr 02 2019In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with the high-quality photometry data from ground-based observations combined ... More
$Spitzer$ Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarfMay 14 2019We report the discovery of a $Spitzer$ microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio $q \sim 2\times10^{-4}$. The planetary signal, which is characterized by a short $(\sim 1~{\rm day})$ "bump" on the rising side of the ... More
Achieving Fully Proportional Representation: Approximability ResultsDec 14 2013We study the complexity of (approximate) winner determination under the Monroe and Chamberlin--Courant multiwinner voting rules, which determine the set of representatives by optimizing the total (dis)satisfaction of the voters with their representatives. ... More
Collective Schedules: Scheduling Meets Computational Social ChoiceMar 20 2018When scheduling public works or events in a shared facility one needs to accommodate preferences of a population. We formalize this problem by introducing the notion of a collective schedule. We show how to extend fundamental tools from social choice ... More
Spitzer as Microlens Parallax Satellite: Mass Measurement for the OGLE-2014-BLG-0124L Planet and its Host StarOct 15 2014We combine Spitzer and ground-based observations to measure the microlens parallax vector ${\mathbf \pi}_{\rm E}$, and so the mass and distance of OGLE-2014-BLG-0124L, making it the first microlensing planetary system with a space-based parallax measurement. ... More
Black Hole, Neutron Star and White Dwarf Candidates from Microlensing with OGLE-IIISep 16 2015Feb 23 2016Most stellar remnants so far have been found in binary systems, where they interact with matter from their companions. Isolated neutron stars and black holes are difficult to find as they are dark, yet they are predicted to exist in our Galaxy in vast ... More